1. Field of the Invention
The present invention relates generally to signature feeders for print machines, and in particular, to a signature registering apparatus for a signature reversing device of a printing machine.
2. Background Information
Packaging, inserting, gathering, stapling and sewing machines receive signature or other paper products to be handled by way of a collection line on which these products are often formed by building them up from a plurality of individual elementary products. In order to form a periodical or a book, for example, a plurality of signatures is generally required. A signature is a printed sheet which has undergone at least one fold but may also indicate groups of printed sheets which are folded together at least once. A group of signatures is typically held in a hopper or feeder which contains the signatures that comprise the periodical or book. It becomes necessary during many handling operations to reverse the direction of signature. Reversing devices are therefore provided to accomplish this objective.
In prior reversing devices the trailing edge of a signature is gripped and removed from the hopper by gripping devices. The gripping devices are arranged on the periphery of a main drum and move the signature along the surface of the drum to a registering stop device via a nip formed between a pinch roller and the main drum. Once registered, the signature is then moved in the reverse direction along the surface of the main drum for further processing.
In order to accommodate skewing of the signature, the entire registration assembly, which includes the pinch roller, was required to rotate in prior reversing devices. Rotation of the entire registration assembly forces the pinch rollers out of alignment with the main drum, thus causing undesired wrinkling or folding of the signature.
The present invention to provides an apparatus for registering a signature moving along a surface in a first direction, the apparatus including: at least one pinch roller for advancing the signature in the first direction; and a register stop for stopping the advancement of the signature, wherein the register stop is rotatable about an axis so as to accommodate a skewing of the signature.
The surface may include a drum, with the pinch roller forming a nip with the drum and the signature passing into the nip.
The pinch roller may be fixedly aligned with the drum.
The register stop may include an end stop for registering the signature and for stopping the advancement of the signature.
The register stop may include an end stop for registering the signature and for stopping the advancement of the signature and may include a stop arm for guiding the signature to the end stop.
A register stop block rotatable about the axis may be provided, the register stop being mounted on the register stop block.
The signature may move along the surface using a propulsion device, which may include a gripper. The propulsion device may disengage the signature using the momentum of the signature.
The register stop may be mounted so that it is urged to return to a neutral position upon a rotation about the axis.
The present invention also provides a method for registering a signature moving along a surface in a first direction, the method including:
advancing the signature in the first direction using at least one pinch roller; and
stopping the advancement of the signature using a register stop, the register stop being rotatable about an axis so as to accommodate a skewing of the signature.
In the present invention, the end stop block and end stop, but not the pinch roller, are rotated. Advantageously, the pinch roller provides a more uniform pushing of the signature into the registration assembly because the pinch roller remains aligned with the main drum. An improved registration and reversing operation, with reduced or eliminated wrinkling or folding of the signature, may thereby be effected.